White House budget director Mick Mulvaney said Tuesday the White House plans to use monies in a border security spending increase to initiate construction of the border wall at the core of President Donald Trump's 2016 campaign.

Mulvaney said the Trump administration will use several hundred million dollars of a $1.5 billion border security spending increase approved in the soon-to-be-approved bipartisan budget deal to begin work on the wall.

"When you heard in the last 48 hours about the deal, did you think we could build this?" Mulvaney said, pointing to a picture of 20-foot high steel wall on the US-Mexico border. "I bet you didn't. Nobody did. OK."

That's despite the fact Democrats touted the agreement as a win and claimed it blocked new funding for border wall construction.

"The (budget deal) does not fund President Trump's immoral and unwise border wall or create a cruel new deportation force," House Minority Leader Nancy Pelosi said Sunday in a statement.

When a reporter asked Mulvaney where the wall in the picture behind him was on the border, he couldn't answer.

Mulvaney also acknowledged the funding won't allow the White House to build "new wall" -- certainly not the massive concrete barriers Trump has so often promised his supporters -- but unveiled the administration's plans to fix and replace existing fencing with a "see-through steel wall."

In recent days, Mulvaney had conceded the budget deal would not allow the White House to build a "bricks and mortar" wall on the border this year.

"There are several hundreds of millions of dollars for us to replace cyclone fencing with 20-foot high steel wall," Mulvaney told reporters Tuesday.

The administration will only be able to use the additional border security funding secured in the budget deal for the 2017 fiscal year because of an existing border fencing law passed by Congress in 2006. Federal officials will only be able to fix or beef up fencing on the less than 700-mile portion of the nearly 2,000-mile long border where fencing has already been erected under that law.

But while Mulvaney acknowledged that the border work funded by the new budget deal would not allow for construction of the full border wall the White House insists it will secure funding for in the next round of budget talks, he also torqued up the spin to tout a win for Trump.

"You can call it new wall, you can call it replacement, you can call it maintenance, call it whatever you want to. The President's priority was to secure the southern border and that's what this does," Mulvaney said.

Earlier in the day, Trump touted the border security funding as a "down payment on the border wall" and also suggested the Democrats had been duped.

"We have more money now for the border than we've gotten in 10 years," he said. "The Democrats didn't tell you that. They forgot. In their notes, they forgot to tell you that. With enough money to make a down payment on the border wall -- I think they will go back and check their papers."

Two senior administration officials said Tuesday that the White House had planned to unveil its plans to replace some existing fencing with steel walls on portions of the border with the new funding during the signing ceremony for the bill.

But Trump and his top advisers grew frustrated with Democrats' claiming victory that they decided to lay out their plans on Tuesday, the officials said.